2. Area: 1 km2 = 100000 m2, 1 m2 = 100 m2, 1 cm2,1hectare =/kloc.

3. Volume: 1 m3 = 1000 cubic decimeter, 1 cubic decimeter = 1000 cubic centimeter;

4. Mass: 1t = 1000kg,1kg =1000 mg;

5. Time: 1 hour =60 minutes, 1 minute =60 seconds.

Extended data:

Commonly used length units are: kilometer {kilometer} (km), decimeter (dm), centimeter (cm), millimeter (mm), micron (micron), nanometer (nm), picometer (pm) and femto meter (fm).

The traditional units of length in China are Li, Zhang, Chi, Inch, Xun, Jie, Fu, Zhi, Yi, Bu, Chang, Ya, Yan, Ji, Rail, Luo, Millimeter, Li and Min. The basic transformation relationship is as follows:

1 ft = 10 ft; 1 ft = 10 inch; 1 inch = 10 points; 1 = 10%;

1 sheet ≈ 3.33m; 1 ft ≈3.33 decimeter; 1 inch ≈3.33 cm;

1km = 1000m； 1 meter (m) = 100 cm; 1 cm =10mm

1 Li = 150 sheets = 500m; 2 Li = 1 km (1000 m).

A few European and American countries, mainly Britain and the United States, use English units, so they use different units of length, mainly miles, yards, feet and inches.

1, mile: 1 mile = 1760 yard =5280 feet = 1.609344 km;

2. yard (yd): 1 yard =3 feet =0.9 144 meters;

3.fath (f, fa): 1 fath =2 yards =1.8288m;

4. Furong: 1 wave =220 yards =20 1. 17 meters;

5. foot (ft, plural): 1 foot = 12 inch =30.48 cm;

6. inch (in): 1 inch =2.54 cm.

The order of area units from small to large is: mm? (square millimeters), centimeters? (square centimeter), dm? (square decimeter), m? (square meters), huh? (hectares), kilometers? (square kilometers). In the International System of Units (SI), the standard unit area is square meters (m2), and the area is a square area one meter long.

Time unit is one of the seven basic units. Length, time, mass, quantity of matter, illumination, current and (thermodynamic) temperature are seven basic units. The time units in this entry are arranged in descending order of time.

Now the daily day and night is 24 hours, while in ancient times it was 12 hours. When western mechanical clocks and watches were introduced into China, people called the time points of China and the West "Da Shi" and "Shi Shi" respectively. With the popularity of clocks and watches, people forget "Da Shi", and "Shi" is still in use today.

A year is a unit of time in which events related to the earth's revolution around the sun in orbit occur repeatedly. Generally speaking, the length of a year is taken as the time interval from a punctuation mark to the same punctuation mark on the celestial sphere along the ecliptic. Because the selected scale points are different, the definition of year is also different, which usually includes:

Last year =365.25964 days

Sidereal year = 365.2563004 solar day (≈ 10 second, 6: 09 in 365)

Tropical year (Bessel year) = 365.245438+099 174 days (≈365 days, 5 hours, 48 minutes and 45.5 seconds).

Leap year =346.62003 (346 days 14 hours, 52 minutes and 52.9 seconds)

In the modern Gregorian calendar, the average year is 365 days (including 52 weeks 1 day), and the leap year is 366 days (including 52 weeks and 2 days).

The seven days of the week are directly translated from Latin. In Latin, Sunday is Sun Day, Monday is Moon Day, Tuesday is Mars Day, Wednesday is Mercury Day, Thursday is Jupiter Day, Friday is Venus Day and Saturday is Saturn Day. French directly adopts Latin names, but changes Sunday to "Sunday"; Because the names of the five planets are the names of gods in ancient Roman mythology.

English has turned some of them into gods in ancient Germanic mythology, such as Tyre, the Teutonic God of War on Tuesday, Frigga, the Teutonic Goddess on Friday, Odin, the Teutonic God on Wednesday and Sol, the Teutonic God on Thursday. In Russian and Slavic, it has become "the first day" and "the second day".

In China, it was probably through the introduction of Zoroastrianism in the 8th century that China got the concept of Zhou and named it [1] after "Seven Obsidian". Japan Obsidian Day is Sunday, Month Obsidian Day is Monday, Fire Obsidian Day is Tuesday, Water Obsidian Day is Wednesday, Obsidian Day is Thursday, Jin Obsidian Day is Friday and Earth Obsidian Day is Saturday. After the founding of the Republic of China, it was renamed Zhou, and the word "star" in it refers to these seven obsidians, but Japan, South Korea and North Korea still use this name.

References:

Baidu encyclopedia-length unit

References:

Baidu Encyclopedia-Area Unit

References:

Baidu Encyclopedia-Time Unit